Synthesis and photoluminescence properties of Mn 2+ doped Ca 1-x Sr x CN 2 phosphors prepared by a carbon nitride based route

International audience ; Mn 2+ doped Ca 1-x Sr x CN 2 phosphors were synthesized by a solid-state reaction in only 1h under NH 3 atmosphere at 700 °C from doped calcium carbonate and carbon nitride as precursors. The samples were characterized by powder X-ray diffraction, scanning electron microscopy and their diffuse reflectance and luminescence properties were investigated in order to evaluate the potential of such systems as red phosphors. All pure and well-crystallized Mn 2+ doped samples exhibit broad red emission around 680 nm when excited at 270 nm at room temperature corresponding to the 4 T 1g (4G) → 6 A 1g (6S) transition. Maximum emission in CaCN 2 :Mn is obtained for Mn 2+ content of 4%mol and is stable up to 343 K and then shows a 20% decrease at 393 K. Finally, the progressive substitution of Sr 2+ for Ca 2+ evidences a solid solution domain between CaCN 2 and β-SrCN 2 with continuous increase of the crystal lattice dimensions. However, such substitution has no impact on the wavelength emission but leads to a decrease of the luminescence efficiency of the phosphor.